CVE-2026-98265 (GCVE-0-2026-98265)
Vulnerability from cvelistv5
Published
2026-10-06 08:45
Modified
2026-10-21 12:54
Severity ?
Summary
In the Linux kernel, the following vulnerability has been resolved: ALSA: usb-audio: Clamp implicit feedback packet count to URB capacity data_ep_set_params() allocates each data URB for exactly u->packets isochronous frames, so urb->iso_frame_desc[] has u->packets slots and ctx->packets is the driver's only record of that limit. For an implicit feedback sink, snd_usb_queue_pending_output_urbs() overwrites it with the sync source's packet count, which is calculated independently from the capture endpoint's parameters. When that count is larger, prepare_playback_urb() and prepare_silent_urb() can write iso_frame_desc[] past the allocation; their existing bounds limit payload bytes, not the descriptor index. The reproducer uses a high-speed UAC2 device declaring bInterval 1 for implicit feedback capture (8 packets) and bInterval 4 for playback (1 packet). On the first capture completion after the stream starts, it accesses seven descriptors spanning 112 bytes beyond the one-packet URB: BUG: KASAN: slab-out-of-bounds in prepare_playback_urb (sound/usb/pcm.c:1560) Write of size 4 at addr ffff88801e696ad0 by task vhci_rx/178 prepare_playback_urb (sound/usb/pcm.c:1560) prepare_outbound_urb (sound/usb/endpoint.c:340) snd_usb_queue_pending_output_urbs (sound/usb/endpoint.c:501) snd_complete_urb (sound/usb/endpoint.c:1834) __usb_hcd_giveback_urb (drivers/usb/core/hcd.c:1657) usb_hcd_giveback_urb (drivers/usb/core/hcd.c:1741) vhci_rx_loop (drivers/usb/usbip/vhci_rx.c:107) kthread (kernel/kthread.c:436) The buggy address belongs to the object at ffff88801e696a00 which belongs to the cache kmalloc-256 of size 256 The buggy address is located 0 bytes to the right of allocated 208-byte region [ffff88801e696a00, ffff88801e696ad0) Record the allocated packet count per endpoint and clamp both the adopted count and the packet-size copy to it. Fold the Format Type II delimiter into urb_packs before the allocation loop so the recorded limit matches every URB.
References
Impacted products
Vendor Product Version
Linux Linux Version: c26bde6301f20d9aafbfb7c2459a88c6a6ec178f
Version: 32a1f64f8ff6e2c5391f5964baec697bce25b83c
Version: e949fd266cfa1dcca7caa3faa698578c4ffd26d6
Version: cf044e44190234a41a788de1cdbb6c21f4a52e1e
Version: cf044e44190234a41a788de1cdbb6c21f4a52e1e
Version: df75696e70c88b22ed1d8c9d515993a858c58fd0
Version: 3a74f6b46c01d9a816378cd83c327a59f61475ec
Version: f6fbdf797e016fbf968dd54301026b182175985a
Version: 6.6.128   ≤
Version: 6.12.75   ≤
Version: 6.18.16   ≤
Version: 5.15.202   ≤
Version: 6.1.165   ≤
Version: 6.19.6   ≤
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{
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "sound/usb/card.h",
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          "product": "Linux",
          "programFiles": [
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            "sound/usb/endpoint.c"
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          "vendor": "Linux",
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              "version": "7.3",
              "versionType": "original_commit_for_fix"
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      "cpeApplicability": [
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              "negate": false,
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      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nALSA: usb-audio: Clamp implicit feedback packet count to URB capacity\n\ndata_ep_set_params() allocates each data URB for exactly u-\u003epackets\nisochronous frames, so urb-\u003eiso_frame_desc[] has u-\u003epackets slots and\nctx-\u003epackets is the driver\u0027s only record of that limit. For an implicit\nfeedback sink, snd_usb_queue_pending_output_urbs() overwrites it with the\nsync source\u0027s packet count, which is calculated independently from the\ncapture endpoint\u0027s parameters. When that count is larger,\nprepare_playback_urb() and prepare_silent_urb() can write\niso_frame_desc[] past the allocation; their existing bounds limit payload\nbytes, not the descriptor index.\n\nThe reproducer uses a high-speed UAC2 device declaring bInterval 1 for\nimplicit feedback capture (8 packets) and bInterval 4 for playback\n(1 packet). On the first capture completion after the stream starts, it\naccesses seven descriptors spanning 112 bytes beyond the one-packet URB:\n\n  BUG: KASAN: slab-out-of-bounds in prepare_playback_urb (sound/usb/pcm.c:1560)\n  Write of size 4 at addr ffff88801e696ad0 by task vhci_rx/178\n   prepare_playback_urb (sound/usb/pcm.c:1560)\n   prepare_outbound_urb (sound/usb/endpoint.c:340)\n   snd_usb_queue_pending_output_urbs (sound/usb/endpoint.c:501)\n   snd_complete_urb (sound/usb/endpoint.c:1834)\n   __usb_hcd_giveback_urb (drivers/usb/core/hcd.c:1657)\n   usb_hcd_giveback_urb (drivers/usb/core/hcd.c:1741)\n   vhci_rx_loop (drivers/usb/usbip/vhci_rx.c:107)\n   kthread (kernel/kthread.c:436)\n  The buggy address belongs to the object at ffff88801e696a00\n   which belongs to the cache kmalloc-256 of size 256\n  The buggy address is located 0 bytes to the right of\n   allocated 208-byte region [ffff88801e696a00, ffff88801e696ad0)\n\nRecord the allocated packet count per endpoint and clamp both the adopted\ncount and the packet-size copy to it. Fold the Format Type II delimiter\ninto urb_packs before the allocation loop so the recorded limit matches\nevery URB."
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-10-21T12:54:54.873Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/8b637ab10e40e01b452f4aff66dad335a9b89a16"
        },
        {
          "url": "https://git.kernel.org/stable/c/ad279ba0dc1781229f5b52f58d38d56960400e06"
        },
        {
          "url": "https://git.kernel.org/stable/c/79c55a7b5d71cf2a6bbd4bd7698e1b10b70f813a"
        },
        {
          "url": "https://git.kernel.org/stable/c/ab77e3f453c5f2499c08d6e8e218501d25bab39e"
        },
        {
          "url": "https://git.kernel.org/stable/c/76a986c980bb502c7688d605ac7a67fd257a9a1b"
        }
      ],
      "title": "ALSA: usb-audio: Clamp implicit feedback packet count to URB capacity",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-98265",
    "datePublished": "2026-10-06T08:45:28.438Z",
    "dateReserved": "2026-09-25T10:25:14.333Z",
    "dateUpdated": "2026-10-21T12:54:54.873Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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